docs: def all_cost_types(self):
          """
          Return the cost types of the computation (including `occupants`
          if it is there) in order.
          """
          # rt has the form 'vulnerability/structural', 'fragility/...', ...
          costtypes = sorted(rt.rsplit('/')[1] for rt in self.risk_files)
          if not costtypes and self.hazard_calculation_id:
              with util.read(self.hazard_calculation_id) as ds:
                  parent = ds['oqparam']
              self._risk_files = get_risk_files(parent.inputs)
              costtypes = sorted(rt.rsplit('/')[1] for rt in self.risk_files)
          return costtypes